Thin sprouts with calyxes?

LED’s have a very small light footprint(the more diodes the more even the footprint). If it was me, I would’ve supercropped (bent at 90 degrees) the leading apical meristem or just chopped it off. Then you can lower your LED to 12-18 inches from the tops and get even light coverage, critically no shade avoidance response, and that will tell the buds to develop. As it is, the top bud is getting too much light and the lowers not nearly enough

One word.... blurple Not enough light, you're not growing that in the led lit footwell of your broken 3 cylinder vauxhall nova on your drive and sit in it banging tunes out your subwoofer charging up the battery by any chance? I say it all the time, should have just bought a bag of weed instead. Learn about plant requirements and how they work and give it a go. I'm sorry for you 😔

Poor genetics, common with auto flowers unfortunately. Yes, a bit early. I wait until there are about 95% brown pistils before starting a flush, then harvest a week or two later when there are about 98-99% brown pistils. This will put your plant in the "10-30% amber trichome" zone without having to look too closely. Hope this helps, Organoman.

Too much nitrogen in Feed I think was your biggest issue here. Very light nitrogen in flowering, especially bulking stage.

it could be genetics... i've had this happen with an autoflower. it is kinda similar to a dr. grinspoon phenotype you can see similar in some red poison and dark devil autos by sweet seeds... bad batches happen. mine was an expert seed. multiple seeds had an issue. if it was environmental, screw plants that are that tempermental anyway. equivalent of the hapsburgh chin, lol.

Too much heat caused buds to stretch searching for cooler air had this happen when I started got better ventilation and it started growing tight big bugs again

Way too soon IMO. There appears to be no browning of stigmas/pistils. Autos run however long they feel, throw the breeder timeline out the window.